I don't own a 250R but my friend is dropping his off at my house and I plan to clean and oil the air filter for him. Is there anywhere I can find pictures of the air filter access? Or is it going to be self explanitory... I just want to know what to expect when he drops it off - I've enver even looked under the seat of one.

 

Pop the seat and fender assembly (just like a 400EX) and the airbox lid is right there. Pretty self explanatory from there like you figured.